7.3 Virtualized network functions (VNFs) and service chaining
3 min read•august 9, 2024
(NFV) transforms traditional hardware-based network functions into software. (VNFs) run on standard servers, offering flexibility and cost savings. They're the building blocks of modern network services.
(SFC) links VNFs to create complex network services. It allows for dynamic reconfiguration and improved service flexibility. VNF Forwarding Graphs define the topology and connectivity between VNFs in a service chain.
Virtual Network Functions
Fundamentals of Virtualized Network Functions
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- Virtualized Network Functions (VNFs) represent software implementations of network functions traditionally performed by dedicated hardware devices
- VNFs run on standard x86 servers or cloud computing infrastructure, enabling flexible deployment and scaling
- Common VNF types include firewalls, load balancers, routers, and intrusion detection systems
- VNFs offer benefits such as reduced hardware costs, improved resource utilization, and faster service deployment
- Virtual appliances package VNFs with a minimal operating system for easy deployment and management
- VNF components include the VNF software itself, the virtualization layer, and the underlying hardware resources
VNF Descriptors and Management
- (VNFD) defines the operational and resource requirements of a specific VNF
- VNFD contains information on VNF identification, connectivity, interface requirements, and scaling rules
- VNFDs use standardized formats ( or ) to ensure interoperability between different NFV platforms
- (MANO) systems use VNFDs to automate VNF lifecycle management
- VNFD elements include VNF identification, (VDU) specifications, and connection point details
- VNF managers utilize VNFDs to handle VNF instantiation, scaling, and termination operations
Service Function Chaining
Principles of Service Function Chaining
- Service Function Chaining (SFC) connects multiple network functions in a specific order to create a composite service
- SFC enables the creation of complex network services by combining individual VNFs
- (NS) represents the end-to-end service composed of multiple chained VNFs
- SFC improves service flexibility, allowing for dynamic reconfiguration of network functions
- Common SFC use cases include security services (firewall, IDS, DPI) and mobile network services (PGW, SGW)
- SFC implementation challenges include maintaining packet flow context and ensuring performance across chained functions
VNF Forwarding Graphs and Orchestration
- (VNF-FG) defines the topology and connectivity between VNFs in a service chain
- VNF-FG specifies the order of VNFs, connection points, and virtual links between functions
- Forwarding graphs support both linear and branching topologies for complex service compositions
- manages the deployment and lifecycle of service function chains
- Orchestrators use VNF-FGs to automate the provisioning and configuration of network services
- allows for real-time modification of service chains based on network conditions or policy changes
Descriptors and Orchestration
Network Service and VNF Descriptors
- Network service descriptor (NSD) defines the structure and characteristics of a complete network service
- NSD includes information on constituent VNFs, their interconnections, and deployment requirements
- NSDs specify service-level parameters such as quality of service (QoS) requirements and scaling policies
- VNF descriptor (VNFD) provides detailed specifications for individual VNFs within a network service
- VNFD elements include resource requirements, interface definitions, and lifecycle management scripts
- Descriptors use standardized data models (, ) to ensure consistency across different NFV platforms
Service Chaining Orchestration and Management
- Service chaining orchestration automates the deployment and management of complex network services
- Orchestrators interpret NSDs and VNFDs to instantiate and configure service function chains
- NFV orchestration functions include , VNF placement, and service scaling
- Orchestrators interact with VNF managers and virtualized infrastructure managers (VIMs) to coordinate service deployment
- Service chaining orchestration enables closed-loop automation for fault management and performance optimization
- Challenges in orchestration include maintaining service continuity during updates and ensuring multi-vendor interoperability
Key Terms to Review (26)
Containerization: Containerization is a method of packaging and deploying applications in lightweight, portable containers that can run consistently across different computing environments. This approach allows developers to encapsulate all the dependencies and configurations needed for an application, promoting efficiency, scalability, and isolation. It connects closely to modern networking paradigms by enabling dynamic deployment and management of services in various infrastructures.
Dynamic service chaining: Dynamic service chaining is the process of creating, modifying, and managing a sequence of virtualized network functions (VNFs) that can be orchestrated on demand to meet specific application requirements. This approach allows for flexible service delivery by enabling VNFs to be dynamically instantiated and interconnected based on real-time network conditions and user needs, which is essential for optimizing resource usage and enhancing user experience.
ETSI: ETSI, or the European Telecommunications Standards Institute, is an independent organization responsible for developing global telecommunications standards. It plays a critical role in the interoperability and harmonization of various communication technologies, which is essential for virtualized network functions (VNFs) and service chaining, ensuring that different systems and components can work together seamlessly within a network architecture.
Etsi nfv: ETSI NFV (European Telecommunications Standards Institute Network Functions Virtualization) is a standardization initiative aimed at promoting the virtualization of network functions to improve operational efficiency and service flexibility. This framework guides how network services are designed, deployed, and managed through the use of virtualized resources, allowing for more agile responses to changing demands and innovative service delivery.
Firewall vnf: A firewall VNF (Virtual Network Function) is a software-based implementation of a traditional firewall that runs on virtualized infrastructure, providing security services for network traffic. This concept connects to network function virtualization (NFV) architecture by allowing firewalls to be dynamically deployed, scaled, and managed within a virtualized environment, enhancing flexibility and efficiency in network security management.
Hypervisor: A hypervisor is a software layer that enables virtualization by allowing multiple operating systems to run concurrently on a single physical machine. It acts as a bridge between the hardware and the virtual machines (VMs), managing their resources and providing isolation. This capability is crucial for efficient resource utilization and flexibility in network architectures, enabling the development and deployment of virtualized services.
Latency issues: Latency issues refer to delays that occur during data transmission across a network, affecting the responsiveness and performance of applications and services. These delays can arise from various factors, such as network congestion, physical distance, processing time, and inefficient routing. In the context of virtualized network functions and service chaining, latency becomes a critical concern as it impacts the overall efficiency and user experience of network services.
Load balancer vnf: A load balancer VNF (Virtualized Network Function) is a software-based solution that efficiently distributes network traffic across multiple servers or resources to ensure optimal performance, reliability, and resource utilization. It plays a critical role in managing the flow of data in virtualized environments, helping to balance the load and prevent any single server from becoming overwhelmed. This not only enhances the overall performance of applications and services but also supports dynamic scaling in response to varying traffic demands.
Management and orchestration: Management and orchestration refer to the processes and tools used to automate, manage, and coordinate the deployment and operation of virtualized network functions (VNFs) and services within a network. This involves overseeing resources, ensuring efficient service delivery, and enabling the dynamic adjustment of network configurations to meet changing demands. The seamless integration of VNFs into service chains relies heavily on effective management and orchestration for optimal performance and resource utilization.
Network Function Virtualization: Network Function Virtualization (NFV) is a network architecture concept that utilizes virtualization technologies to manage and deploy network functions as software instances on general-purpose hardware, rather than relying on dedicated physical devices. This approach enhances flexibility, scalability, and efficiency in network management, allowing operators to respond quickly to changing demands and optimize resource utilization.
Network service: A network service refers to the various functions and operations that are provided to users or applications over a network, facilitating communication and data exchange. These services can be delivered through physical devices or virtualized network functions and play a crucial role in ensuring efficient connectivity, data transfer, and network management. The implementation of network services is integral to concepts like Virtualized Network Functions (VNFs) and service chaining, as they help streamline the process of delivering network capabilities in a dynamic and scalable manner.
ONAP: ONAP, or Open Network Automation Platform, is an open-source software framework designed to manage and orchestrate network functions in a virtualized environment. It enables service providers to automate the deployment and lifecycle management of Virtualized Network Functions (VNFs), streamlining operations and enhancing network agility. By integrating with various tools and components, ONAP plays a critical role in enabling service chaining and facilitating the management of network resources.
OpenFlow: OpenFlow is a communications protocol that enables the separation of the control and data planes in networking, allowing for more flexible and programmable network management. By using OpenFlow, network devices can be controlled by external software-based controllers, making it a foundational component of Software-Defined Networking (SDN) architectures.
Resource Allocation: Resource allocation refers to the process of distributing available resources, such as bandwidth, computing power, and storage, to various network functions and services to optimize performance and efficiency. This involves dynamically assigning resources based on current demands and predefined policies, ensuring that multiple users or tenants can coexist within the same infrastructure while meeting their specific requirements.
Scalability: Scalability refers to the ability of a network or system to accommodate growth and handle increased demand without sacrificing performance. In the context of software-defined networking (SDN), scalability is essential as it allows networks to expand seamlessly, integrating new devices and services while maintaining efficient operations.
Service chaining orchestration: Service chaining orchestration refers to the management and arrangement of multiple virtualized network functions (VNFs) into a coherent service chain that delivers specific network services. It coordinates the interactions between VNFs to ensure efficient and dynamic routing of data packets, enabling users to benefit from a tailored service experience. This orchestration plays a crucial role in optimizing resource utilization and enhancing network performance in a Software-Defined Networking environment.
Service Function Chaining: Service function chaining is a networking concept that allows for the orchestration of multiple virtualized network functions (VNFs) into a defined sequence or chain. This enables dynamic and flexible deployment of services such as firewalls, load balancers, and intrusion detection systems, improving overall network efficiency and performance while supporting multi-tenancy and network slicing.
TOSCA: TOSCA, or Topology and Orchestration Specification for Cloud Applications, is a specification that describes the structure of cloud applications and their components. It provides a way to define the services, networks, and resources needed to deploy and manage virtualized network functions (VNFs) effectively. This helps in automating the deployment process and enables service chaining by connecting different VNFs together seamlessly.
Virtual Deployment Unit: A virtual deployment unit is a software-based construct that encapsulates the necessary components for deploying and managing virtualized network functions (VNFs) within a virtualized infrastructure. It enables flexible and scalable network services by allowing multiple VNFs to be orchestrated together, optimizing resource usage and reducing operational costs. This concept is essential for implementing service chaining, where different VNFs are connected to deliver complex networking functionalities.
Virtual Network Function Manager: A Virtual Network Function Manager (VNFM) is a key component in the orchestration and management of virtualized network functions (VNFs). It is responsible for the lifecycle management of VNFs, which includes their instantiation, scaling, and termination. The VNFM ensures that VNFs are deployed efficiently, monitored for performance, and can be updated or removed as necessary within a service chaining framework, thereby enhancing the flexibility and scalability of network services.
Virtualized network functions: Virtualized Network Functions (VNFs) are software-based implementations of traditional network functions that are designed to run on virtualized infrastructure, such as cloud environments. VNFs allow for increased flexibility, scalability, and efficiency by decoupling network functions from the hardware they traditionally run on, enabling dynamic service chaining and resource allocation.
Vnf descriptor: A VNF descriptor is a comprehensive blueprint that defines the properties, characteristics, and requirements of a Virtualized Network Function (VNF) within a network service. It includes essential information such as the software images needed, deployment parameters, scaling rules, and interfaces for connecting to other VNFs or network resources. This descriptor plays a critical role in service chaining, ensuring that different VNFs can work together seamlessly to deliver complex network services.
Vnf forwarding graph: A VNF forwarding graph is a representation of how virtualized network functions (VNFs) are interconnected to process and route network traffic in a service chain. This graph outlines the sequence of VNFs that data packets traverse, defining the flow of traffic and enabling flexible service deployment, management, and scaling in software-defined networks. It plays a crucial role in orchestrating the relationships between VNFs to ensure efficient service delivery.
XML: XML, or eXtensible Markup Language, is a markup language designed to store and transport data in a format that is both human-readable and machine-readable. It provides a flexible way to create information formats and share structured data across different systems, making it a vital component in various applications, particularly in networking and web services.
Yaml: YAML, which stands for 'YAML Ain't Markup Language', is a human-readable data serialization format that is commonly used for configuration files and data exchange between languages with different data structures. It is particularly popular in the context of cloud computing and software-defined networking for defining and orchestrating virtualized network functions (VNFs) and service chains due to its simplicity and ease of use, allowing developers to describe complex configurations in a clear and concise manner.
Yang: Yang is a data modeling language used to define the structure and behavior of data in network configurations and services. It enables the development of standardized data models that can be utilized across various network functions, promoting interoperability and flexibility in managing virtualized resources and applications. Yang plays a crucial role in enhancing automation and programmability in networking environments.